1. Field of the Invention
The present invention relates to a brake device for a powered chain saw.
2. The Prior Arts
A portable chain saw, which is powered by a diesel fuel engine, is commonly used in gardening and a logging activity. The engine drives a driving shaft, as well as a chain wheel and a chain connected to the driving shaft to rotate, such that a saw blade coupled to the chain can cut a work piece. As the engine is shut down, the driving shaft will continue rotating for a while because of the rotational inertia. Since the saw blade on the chain saw is very sharp, an accident may occur once the operator is careless.
For this reason, there are many related brake devices developed recently to reduce the risk of using the powered chain saw. When the engine is shut down, or even an accident occurs, the operator can use such a brake device to stop the rotation of the driving shaft immediately. However, the traditional brake devices for a powered chain saw have several disadvantages, such as excessive parts, complicated structure, heavy weight and high manufacturing cost.